(I work at Google) Yes, internally we all use Jetski (internal version of Antigravity). Outside of Gemini, Opus models are supported and allowed for internal use. No OpenAI models since they are not on Vertex

Claude used to be GDM only, but recently opened up Opus for all googlers

No way to run OAI on a machine with monorepo access even if you wanted to. Claude runs on Vertex so it's not leaving Google infrastructure.